Radar systems are useful for detecting, characterizing and monitoring various kinematic parameters associated with natural and/or man-made objects and are critical to both civilian and military operations. These systems typically transmit “beams” or electromagnetic (EM) signals intended to engage one or more objects or targets, and process reflected return signals (or echoes) for measuring spatial features, object identification and characterization. A radar echo return usually contains both signals generated from a desired target, as well as background clutter. Clutter returns arise from reflections from stationary and/or moving background objects (e.g. precipitation, terrain, debris etc.). This clutter decreases radar performance by hindering the system's ability to detect true targets and/or increases the probability of undesirable target detections.
Numerous methods exist which attempt to discriminate between unwanted clutter and return signals resulting from desired targets. Many of these employ clutter cancellation methods that rely on the principle that moving targets have a Doppler frequency shift, while stationary targets do not. Thus, pulse-Doppler radar systems may implement a plurality of Doppler frequency filters (e.g. FFT networks) used to divide the Doppler frequency space into many narrow regions, with each filter corresponding to one of these frequency bands. Knowing the frequency space normally associated with specific clutter types, these Doppler filters can be used to discriminate against clutter, as well as identify target Doppler frequency.
Processing may also be used to discriminate between moving targets of interest and unwanted objects or clutter displaying similar velocity profiles. Current systems rely on the analysis of radar cross-section or an object's kinematics (e.g. its velocity or Doppler) and derived acceleration characteristics in the time domain for discrimination between true targets and unwanted clutter with characteristics resembling desirable targets. However, these systems are unable to discriminate between objects with simple dynamic motions, and those having complex dynamic motions. More specifically, these systems lack the ability to, for example, to distinguish between an object maintaining a fixed attitude (i.e. simple dynamic motion), such as an aircraft, from objects possessing no method of attitude control and whose motion is purely random (i.e. complex dynamic motion), such as debris.
Accordingly, improved systems and methods for discriminating between objects displaying simple and complex dynamic motion are desired.